The Big Rocks of Sprint Mechanics

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When I began my journey to learn how to coach speed one of my first stops was Altis. While I’ll continue learning from many sources, it’s hard to imagine a future in which I’m not grounded in the fundamentals I’ve learned through the Altis Foundation course.

It’s long, it covers a LOT of material—basic physiology / biomechanics, developing an annual training plan / coaching philosophy, athlete psychology, sprint mechanics, and more—but every bit of it is designed to be immediately applied and to, well, build your foundation as a coach.

A+ in my book (and I’m not even getting paid to write this!).

The only moan and groan I can muster is that sprint mechanics—the #1 reason for I purchased the course—is the very last topic covered.

It was worth the wait.

Sprint Mechanics: faster, safer athletes

In general, a ton of information exists on weight room work and very little information is available on how to teach and develop sprint speed.

Maybe this is why many strength and conditioning coaches aren’t well versed in sprint mechanics and have little to no clue how to go about teaching speed. We are experts at making you stronger, but not at all in identifying injurious or inefficient sprint patterns.

It’s not a knock on S&C professionals at all, it’s simply an observation about the state of our field in this moment.

Just as with resistance training, there are biomechanical factors during the sprint cycle that predispose an athlete to experiencing injury. A violent inward collapse of the heel during ground contact (foot external rotation moment), for instance, places undue shear forces on the Achilles tendon and can cause crippling—or career ending—Achilles pathology if not addressed.

Understanding biomechanics is key for helping an athlete negotiate such avoidable injuries.

Of course, another benefit of proper biomechanics is improved performance. In the weight room this is easy to see—bar speed improves or the athlete reports a lower RPE after adopting a new cue into their technical execution.

Sprinting is no different. Proper biomechanics lead to optimal force production and orientation when sprinting.

The bottom line is: athletes who improve their sprint technique get faster.

The Big Rocks of Sprint Mechanics

Throughout a sprint:

  • Stride frequency increases
  • Ground contact times decrease
  • Body angles change
  • Stride length increases
  • Flight times increase
  • All of this happens in sync

We must understand the final item on that list before diving into the others.

Sprinting is like an orchestra: many different moving parts, but all must be on the same page and approach the crescendo in sync. If one musician gets too excited and rushes it, the whole orchestra is off.

To maximize sprint performance, the athlete must control his or her kinematics and change body posture and technique in a similar format: in sync, on the same page, not with one big rock changing at a faster rate than another.

Stride frequency increases

Understanding stride frequency has been a game changer in how I think about speed and sprinting.

Stu McMillan, CEO and sprints coach at Altis, posed a question in the Altis Facebook group:

Would acceleration technique be different if the task was 10m, rather than 100m?

My original thought was: no, in a 100m dash you want to run as fast as possible from start to finish, and in a 10m dash it’s the same.

Boy, was I wrong.

Top speed in a 100m dash is held for 20-30m at most. After that the athlete begins to decelerate.

Most elite sprinters hit that top speed window somewhere between 60-90m in a 100m dash. Sub-elite sprinters hit it sooner.

When an athlete seems to be “pulling away from the pack” at the end of the race, it’s not that she is speeding up, it’s that she is decelerating at a slower rate than the others.

It’s like racing model cars down a slope. Once they hit the straight away they’re all slowing down. The winner is the one who maintains as much speed as possible, or, in other words, who decelerates the slowest.

Because max velocity is a product of stride frequency and stride length, if stride frequency increases too quickly, max velocity will be achieved at earlier stages in the race, meaning the athlete will begin deceleration earlier in the race.

This is not an optimal strategy.

A gradual, more patient acceleration results in faster 100m times. The athlete is sprinting as fast possible as soon as the gun goes off, but has longer ground contacts which results in a lower frequency early in the sprint efforts.

Which leads us to…

Ground contact time decreases

Ground contact is inversely related with sprint speed at a given moment. That is, as an athlete gains speed, ground contact time decreases. This happens naturally.

Longer ground contact times during the acceleration phase allows for greater force application in the ground. The longer the foot is on the ground, the more time it has to push you forward.

This is how stride frequency can be manipulated during acceleration. Spending more time on the ground during the first several steps (6-10) allows for a crescendo-like build in stride frequency.

Athletes who have poor ground contact patterns look choppy instead of smooth in the first steps of a sprint, and have poor acceleration speed because of it.

Body angles change

Attack angle, also known as projection angle, is the angle at which force is applied into the ground during acceleration. It should be between 36-55 degrees coming out of the blocks for track and field athletes. More elite athletes can project at lower angles (more horizontally) without stumbling and falling on their face, while sub-elite athletes lack the skill or power to do so.

Athletes other than track sprinters should project (begin acceleration) at as steep an angle as possible without stumbling and sacrificing the other mechanical big rocks. 45 degrees is a baseline angle to work from, adjusting up or down dependent on athlete ability.

Attack angle in the first step of a standing start.

During acceleration the shin angle should match the torso angle upon touchdown (when the swing-leg foot first makes contact with the ground).. At max velocity, the torso should be nearly vertical with a slight forward lean and shin angle should be near vertical upon touchdown, with the heel directly under the knee.

Shin and torso angles are not parallel, demonstrating sub-optimal technique.

Importantly, these angles should all change together, in rhythm and in sync. It is not ideal for the athlete to maintain a forward lean by bending at the waist during acceleration, as is typically seen. In this case shin and torso angles don’t match and the results is slower, less efficient acceleration.

The elbows should open during the backswing and close as the arm swings forward. Elbows should not remain locked at 90 degrees while sprinting.

Stride length and flight time increases

These two topics seem to take care of themselves if the three aforementioned principles are adhered to, but serve as other points to monitor.

Athletes who over-push horizontally at max velocity sacrifice flight time, which interferes with the ability of the swing leg to fully recover and block (stop) in front to set up and efficient ground contact. The result is less force exerted onto the ground, smaller stride lengths, and a lower max velocity.

Thus, stride length is partly a function of flight time, and flight time is a byproduct of quality sprint mechanics.

Smooth, congruent sprinting

Of course subtleties exist and this is not a comprehensive list of every KPI of sprint mechanics. These are the big rocks, the starting points.

But it athletes have these basics down then they have a solid foundation on which to grow.

Just as we have a responsibility to teach athletes how to lift and help them grow stronger, we have a duty to teach and ensure the basics of sprint technique to further improve performance, elevate the ceiling of their performance potential, and most importantly, to decrease the likelihood of injury.

These big rocks are a great place to start.


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